Automatic shut-off mechanism for a printing machine



Sept. 6, 1969 J. JANECEK ETAL 3,467,372

AUTOMATIC SHUT-OFF MECHANISM FOR A PRINTING MACHINE Filed Sept. 18, 1967 2 Sheets-Sheet l IVNVENTORS 75/05/00- 75/1! #6, 21/705 /azf )1! e/lK P 1969 J. JANECEK ETAL 3,467,372

AUTOMATIC SHUT-OFF MECHANISM FOR A PRINTING MACHINE Filfid Sept. 18, 1967 2 Sheets-Sheet 2 v INV'ENTORS Eras/a0 75/7 eceK MAM/a BY )Was e// MMM,

United States Patent 3,467,372 AUTOMATIC SHUT-OFF MECHANISM FOR A PRINTING MACHINE Jaroslav Janeek, Brno, and Miloslav Muselik Ricmanice, Czechoslovakia, assignors to Adamovske Strojiruy, narodni podnik, Adamov, Czechoslovakia Filed Sept. 18, 1967, 668,409 Int. Cl. B65h 7/02, 3/08 US. Cl. 271-56 5 Claims ABSTRACT OF THE DISCLOSURE Background of the invention This invention relates to sheet-fed printing machines, and particularly to an automatic shut-off mechanism for stopping such a machine when its carrier for printed sheets is loaded to full capacity.

Many conventional sheet-fed printing presses are provided with a carrier for the printed sheets, which moves downward as the printed sheets accumulate thereon, whereby the discharge of the printed sheets from the cylinders of the machine is greatly facilitated. The capacity of the carrier is limited and is normally insufficient to accept all sheets of a very long run. It is necessary, therefore, to stop the press while the stack of printed sheets is being removed from the carrier.

It is known to stop the drive shaft of such a press automatically when its descending sheet carrier is loaded to capacity. The machine is arrested thereby while in its full operating condition. Some sheets may be partly shifted from the feed table and others may be located between the printing cylinders. Printing cannot be resumed until these partly processed sheets are removed because they would not only be objectionable themselves but would cause the production of additional rejects. Removal of the sheets is time-consuming and particularly diflicult in rotary offset machines in which paper sheets tend to cling to the rubber covers of the cylinders.

The object of the invention is the provision of a shut-off mechanism which leaves the printing press free of partly processed sheets when shut down automatically in response to full loading of the printed sheet carrier.

Summary of the invention The shut-off mechanism of the invention is applicable to all sheet-fed printing machines equipped with at least one suction feeder operated by a vacuum system and provided with a carrier which moves downward as the printed sheets accumulate thereon.

It includes a valve interposed between the vacuum system of the feeder and the ambient atmosphere and movable between an open position in which the system is connected to the atmosphere by the valve, and a closed position. Cooperating abutments on a printed sheet carrier and the valve move the latter into the open position in response to the downward movement of the carrier, thereby venting the vacuum system and making the feeder inoperative.

The shut-01f mechanism may further include a conventional electrical circuit for deenergizing the drive motor ice of the press when the carrier reaches a position of full capacity load, at some time after the venting of the vacuum system so that all sheets fed to the machine are fully processed and discharged when the press cylinders come to a halt.

Other features and many of the attendant advantages of this invention will be appreciated readily when the same is better understood by reference to the following detailed description of a preferred embodiment when considered in connection with the attached drawings.

Brief description of the drawings In the drawings:

FIG. 1 shows a shut-01f mechanism of the invention in side elevation;

FIG. 2 shows the same mechanism in front elevation; and

FIG. 3 illustrates a sheet-fed rotary offset printing machine equipped with the shut-off mechanism of FIGS. 1 and 2 in a side-elevational fragmentary view.

Description of the preferred embodiment Referring to the drawings in detail, and initially to FIG. 3, there is seen as much of a conventional sheet-fed rotary offset printing machine with electrical motor drive, as is necessary for an understanding of the shut-off mechanism with which this invention is more particularly concerned.

The housing 20 which obscures most of the operating elements of the printing machine in FIG. 3 has been partly broken away to show the feed table 16 and a suction feeder 15 which feeds blank sheets from the table to the printing cylinders, not themselves visible. The feeder 15 is connected to a rotary vacuum pump 18 by a vacuum hose 14 and a control valve 17. The printed sheets discharged from the cylinders of the press are stacked on a carrier 7 which moves downward as the sheets accumulate thereon. The machine described so far is conventional, and does not require more detailed description.

A vacuum hose 10 connects the pump 18 to a body 1 of a venting valve which is mounted by a bracket 13 on the machine housing 20 and is operated by means of an arm 3 when the latter is engaged by an abutment pin 8 on the carrier 7. This shut-off mechanism is illustrated in greater detail in FIGS. 1 and 2.

The valve body 1 has a horizontal bore which is open in both axial directions and provided with a tubular liner 2 coaxially rotatable in the bore of the valve body 1 in sealing engagement with the same. In the position illustrated in FIG. 1, a radial passage 2 through the liner 2 is aligned with inner orifice 1' of a similar passage through the valve body 1 from which a nipple 9 projects outwardly. The afore-mentioned vacuum hose 10 connects the nipple 9 to the vacuum pump 18.

One axial end of the liner 2 carries the fixedly attached operating arm 3 whose free end is forked, the branches 3', 3" of the forked end being substantially vertically spaced in all operative positions of the arm 3. Opposite cam faces of the branches 3, 3" flare obliquely in a radially outward direction from the axis of the liner 2.

A helical tension spring 4 is mounted between a pin 5 in the median plane of the arm 3 near the forked end and a pin 6 arranged on the valve body 1 in such a manner that the effective length of the spring 4 between the pins 5, 6 reaches a minimum in the open position of the valve illustrated in FIG. 1 in fully drawn lines, and another minimum in the closed valve position in which the arm 3 assumes a position shown in broken lines. The spring 4 is stretched when the arm 3 moves from either position toward the other.

A bracket 12 attached to the bracket 13 carries a microswitch 11 whose operating button 11 is covered by a cam-shaped leaf spring 19 one end of which is attached to the switch housing. The free end of the spring 19 is well below the lower branch 3 of the arm 3 in the closed valve position.

The shut-off mechanism described above operates as follows:

When the carrier 7 approaches the lower limit of its downward movement under a full-capacity load of printed sheets, and the orifice 1' of the valve body 1 is sealed by the liner 2 in the closed valve position, the abutment pin 8 engages the branch 3' of the operating arm 3 and turns the arm clockwise, as viewed in FIG 1. When the spring 4 has thereby been stretched to its greatest effective length, the contracting spring accelerates the angular movement of the sleeve 2 toward the fullydrawn open valve position so that the branch 3' is lifted from the pin 8, and the branch 3" strikes the pin 8, as shown in FIG. 1.

During further downward movement of the carrier 7, an ,edge portion of the carrier 7 engages the cam-shaped spring 19 and thereby depresses the button 11' of the micro-switch 11. The micro-switch is an element of the control circuit, not otherwise shown, which stops the electric drive motor of the press when the button 11' is depressed, the circuit including conventional relays and magnetic switches connected in a conventional manner.

When the orifice 1 of the valve body 1 is first opened to the atmosphere by the liner 2, air enters the vacuum system at a high rate, and the suction at the feeder 15 becomes insufiicient for lifting additional blank sheets. No further paper is fed to the machine although the vacuum pump 18 continues to be driven by the electric motor of the machine. All previously fed sheets are fully processed and discharged before the spring 19 is engaged by the carrier 7, and before the motor is deenergized, thereby stopping the vacuum pump 18 and the printing cylinders (not shown).

After unloading of the carrier 7, and during return of the carrier 7 to its topmost position, the spring 19 is released, thereby starting the drive motor of the press and the pin 8 abuttingly engages the branch 3 of the arm 3 to return the liner 2 to the valve closing position. The press is ready to resume printing.

It should be understood, of course, that the foregoing disclosure relates not only to a preferred embodiment of the invention and that it is intended to cover all changes and modifications of the example herein chosen for the purpose of the disclosure, which do not depart from the scope and spirit of the invention set forth in the appended claims.

We claim:

1. In a printing machine having an electric drive; a suction feeder operated by a vacuum system; a receiving carrier for printed sheets, said carrier moving in a downward direction as the printed sheets accumulate thereon; and a shut-off mechanism for interrupting operation of said machine in response to the downward movement of said carrier; the improvement in the shut-off mechanism which comprises:

(a) valve means interposed between said vacuum system and the ambient atmosphere and movable between an open position in which said system is connected to said atmosphere by said valve means, and a closed position; and

(b) abutment means on said carrier and on said valve means, provided to cooperate with each other and to serve as said. shut-off means by moving said valve means into said open position in response to said downward movement of said carrier.

2. In a machine as set forth in claim 1, said valve means including a valve body formed with a bore open to said atmosphere and having an axis, a tubular member received in said bore for angular movement about said axis in sealing engagement with said body, said member being formed with a radial passage therethrough, and said body having an orifice alignable with said passage by rotation of said member, and connecting means connecting said orifice with said vacuum system; and said abutment means including an operating arm attached to said member.

3. In a machine as set forth in claim 2, said valve means further including a tension spring interposed between said arm and said body, the effective length of said spring being smaller in said open and closed positions of the valve means than during movement of said valve means between the open and closed positions thereof.

4. In a machine as set forth in claim 2, said abutment means further including a pin member on said carrier, said arm having a forked free end remote from said tubular member and mounted to receive said pin member between the branches of said forked member.

5. In a machine as set forth in claim 1, said electric drive including a switch having an operating member, said abutment means including two abutment portions on said carrier positioned for sequential abutting engagement with said abutment means of said valve means and thereafter with said operating member.

References Cited UNITED STATES PATENTS 2,861,805 11/1958 Auer 271-88 3,306,475 2/1967 Mays 27188 3,103,355 9/ 1963 Hubbard 271-5 RICHARD E. AEGERTER, Primary Examiner 

